Transformer oil



Patented Jan. 12, 1932 STA as BERTRAND W. STORY, OF WOODBURY, NEW JERSEY, ASSIGNOR T V ACU UM OIL COMPANY, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK TRANSFORMER OIL No Drawing.

The present invention relates to transformer oils and an object thereof is to provide an oil having improved property with respect to the formation of insoluble sludge when subjected to oxidation, without introducing at the same time other properties of an undesirable nature such as poor electrical characteristics, aflinity for moisture and high vapor pressure.

Transformer oils, as made by properly refining certain petroleum fractions, gradually oxidize in service and, in those types of transformer oil to which my invention relates, there occurs ultimately a formation of insoluble sludge. This precipitation of sludge is highly objectionable since it is usually less soluble in cool oil than in hot oil and precipitates in the cooling ducts of the transformer. Being a good insulator the sludge prevents the oil from giving up its heat causing the temperature of the transformer to rise beyond safe working limits. WVhen sludge precipitates from oil in a transformer it is customary practice to remove the oil for reconditioning or replacement by new oil; a matter of considerable trouble and expense.

In order to retard the sludging tendency of said transformer oils, it has been proposed to introduce therein glycerine. This suggestion has been found, however, of little practical value, due to the fact that the I use of glycerine in transformer oils causes other effects of an undesirable nature, as for instance, a reduction of dielectric strength and specific resistance.

I have discovered that the sludging tendency of transformer oils can be retarded, without introducing, at the same time, undesirable properties, such as aflinity for moisture and high vapor pressure, by introducing an alcohol having substantial anti-oxidizing qualities, combined with a relatively low vapor pressure and affinity for water. The material which I have found most available for this purpose is cetyl alcohol.

In illustration of my invention, I will describe the retarding effect on the sludging tendency of a transformer oil as determined in the life test for transformer oils (A. S.T.

Application filed March 31, 1926. Serial No. 98,921.

M., report of committee D-9, page 17 publications of American Society for Testing Materials, Philadelphia, Penna), brought about by the addition of cetyl alcohol mss to said transformer oil.

A transformer oil, having a specific gravity of 0.9 and a-viscosity of seconds at 104 F. gave a life test of 16 days when tested according to the method specified above. The addition of one-tenth of one percent by weight of cetyl alcohol increased the life test of said transformer oil to 26 days; while the addition of five-tenths of one percentof cetyl alcohol increased the life test of said transformer oilto 50 days.

Any alcohol, such as glycerine, having a high aflinity for moisture will necessarily impair the dielectric strength and specific resistance of an oil into which it is introduced. Alcohols having a carbon-atom content of more than seven are relatively nonhygroscopic. To this fact the value of cetyl alcohol may be largely attributed, and other alcohols of hi h carbon-atom content may be expected to have similarly valuable'qualities, though not now commercially available for the use in question.

While, in the above illustration of my invention, I have described the desirable effects of certain proportions of cetyl alcohol when added to a given transformer oil, I wish it understood that I do not limit myself to any specific proportions of this alcohol or of any other alcohol coming within the scope of my invention.

What I claim as myinven'tion and desire to secure by Letters Patent is:

A petroleum transformer oil having added thereto cetyl alcohol.

BERTRAND W. STORY. 

